51% attack will not make it richer ... who want buy that coin after the attack is performed ?

He will never get back the investment he put on that attack.

Notice that a simple hard fork by the community will restore everything and allhis efforts will be nulled.

First of all there's several reasons why a majority attack isn't viable, and quite simply isn't worth it. I'm not sure where you've got the 6 billion figure from, and I haven't done any math to support or go against that claim. So, I'll just ignore it for now.

For a 51% attack to be effective a majority attack would have to be maintained constantly to be effective.  Not only that but, several people wanting to protect Bitcoin would likely increase their computing power to protect from a majority attack whether this be 'normal' miners or other countries which support the movement of Bitcoin. For example, there's multiple pools which normal users could band together to reduce the computing power of the malicious attacker. This could be a community driven effort which the majority of worth well users would contribute to one way or another. Whether that's funding or actually providing their computing power.

A 51% attack isn't that effective, and there's probably better ways to go about 'attacking' the Bitcoin network.

Interesting premise however this does not address the issue of lack of liquidity and any given Market, a 51% attack would be possible if it was executed over a large period of time but it's also possible that individual networks would become wise to State action, if this is not the case and an individual cryptocurrency fails to be vigilant and protect their Network it's simply a case of needing to hard Fork and reverse the Damage Done

technology progresses rich power and states stay, if they want they can indefinately break bitcoin

jes i am currently wirting an article about the natural drive for monopolisation which exists in societies observable in board game like "monopoly" but also described in real life by for example karl marx, will also exist within cryptocurrencies and the distribution of hashpower,

we will sooner or later have a huge monster in our midsts that first feeded on the smal coins, and then grew reinvested and then feeded on the big coins, the entire economy then will basically live of the mercy of that association hashpower miners that runs the huge hashpower, similar like the banking cartel, plus it will also be a centre of bitcoin.

i seriously think POW is damn doomed.

Refer to Bitcoin Jesus's video below. He says it quite well.
https://www.youtube.com/watch?v=ncPyMUfNyVM

There is no way that a government gets hold of and installs millions of antminers, powers them and manages to sustain the attack. Think of the logistics behind it. Consider how much electricity they will need, they will probably need to power down their entire country, and after all that they can just do one double spend.

Bitcoin is designed in a way that ensures that the actors that could theoretically
harm the network are heavily incentivized to actually play by the rules.

You claim that a potential problem lies in the possibility that the big mining
pools "associate themselves". Why would the miners collude to harm Bitcoin?
If they seriously damage the trust in Bitcoin they lower the profits for future mining
and also lower the value of their infrastructure and their hardware.
Besides, a successful attack on Bitcoin would seriously damage the trust in
all cryptocurrencies. It´s not like they could just use their miners to mine
another cryptocurrency after an attack on Bitcoin.

These attack scenarios are relevant for small PoW coins (see the recent attacks
on Bitcoin Gold, Monacoin or Verge), but Bitcoin is basically
immune to this particular threat.

One would think this is one of the key reasons that they’re unlikely to short the token and attack, unlike proof-of-stake. However, the miners concoct all sorts of drama (e.g. block size forks) in order to drive the prices down and up like a yoyo, because they profit on the swings in price and they mine multiple tokens and arbitrage between them. Also the lowest cost miners can use price swings to squeeze the marginal miners. The capitalists who own the 12/14nm ASIC foundaries decide who gets the most efficient ASICs first.

The mining cartel doesn't want to outright double-spend or break the protocol yet, because they're still nurturing this 666 system they’re hoisting on us. Yet I am not in some fantasyland dream where I think they're not manipulating on both the down and upside.

Sorry for the depressing thoughts. I like realism, not fantasies.

I dont think the u.s will do this even if it is thrue that they ar3 capable of doing this. Not unless bitcoin poses a threat to their national security. And so far I can see that bitcoin is actually helping boost the economies of those countries so accepted it. It fucoses more on the business and fluidity of transactions in any person's daily activities. It helps makes life or living better and faster and more convenient so i dont see a any reason that the u.s would get rid of crypto.

I think countries will not want to do that, because it's potential